Seed firming wheel for grain drills and the like

ABSTRACT

A seed firming wheel attachment is disposed behind the paired discs of an opener to gently press deposited seeds down into the bottom of a V-shaped trench formed by the discs. An improved bearing assembly couples the wheel of the attachment to its support arm in such a manner that one side face of the upright wheel is left completely smooth and flat without projecting nuts or other structures that would tend to accumulate mud and trash. The solid, unbroken expanse of the smooth side face also serves to shield the bearing assembly against exposure to the elements from that side of the wheel. A specially configured inner race of the bearing assembly has a shaft portion that extends from the opposite side of the wheel to serve as a spacer between the wheel and its support arm, a receiver for the threaded fastening bolt of the assembly, and a sealing surface for a second, resilient, annular seal of the assembly against the elements.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.07/850,559, filed Mar. 13, 1992, now U.S. Pat. No. 5,398,625 entitledGRAIN DRILL UNIT HAVING SEED FIRMING WHEEL, said application beingincorporated herein by reference.

TECHNICAL FIELD

This invention relates to grain drills and, more particularly, to a seedfirming wheel assembly which accompanies the double-disc opener of sucha drill for gently pressing deposited seeds down into the loose soil atthe bottom of a trench formed by the two discs of the opener.

BACKGROUND

After seeds have been deposited in a trench formed by a pair of openerdiscs, it is desirable to press the seeds gently down into the soil atthe bottom of the trench before the trench is then covered over withsoil by the trailing press wheel. A variety of small firming wheels haveheretofore been provided by various manufacturers for accomplishing thisfunction.

However, one nagging problem associated with currently available firmingwheels is the accumulation of trash residue and mud in and around thefirming wheels. When the buildup of this type of material becomes greatenough, it will actually interfere with the rolling action of the wheeland may cause it to stop rolling all together, turning the wheel intomore of a gouging device than something that gives the seed its finalsetting into place.

SUMMARY OF THE INVENTION

Accordingly, one important object of the present invention is to providea seed firming wheel assembly, particularly usable in connection withthe paired opening discs of a grain drill, which gently yet firmlypresses the deposited seeds into the soil at the bottom of the trenchprepared by the discs while minimizing the opportunity for thecollection and buildup of trash crop residue and mud. More particularly,in an opener in which there is a press wheel which trails the firmingwheel and the press wheel is utilized as a means for gauging the depthof the discs, it is an important aim of the invention to provide forgentle firming action on the part of the seed firming wheel withoutcausing the firming wheel to take over the depth gauging function of thepress wheel. In other words, an important consideration is to provide afirming wheel which is capable of carrying out its delicate seed firmingfunction without adversely affecting the ability of the press wheel tocarry out its depth gauging function.

Another important object of the present invention is to provide analternative seed firming wheel assembly that reduces the opportunity forthe collection and build-up of crop residue and mud on the wheelassembly and undergoes reduced seal drag, especially in wet operatingconditions.

Pursuant to the foregoing, the present invention contemplates having aseed firming wheel assembly which is mounted in a close-coupledrelationship with the rear extremities of the paired discs so that thereis little, if any, space behind the discs for trash and mud toaccumulate on the wheel assembly. In order to accomplish this closecoupling relationship, relatively slender mounting structure is arrangedin the narrow space between the paired discs along their rear margin,and only that portion of the assembly having a width which mightinterfere with the discs is positioned rearwardly beyond the discsthemselves. While a primary mounting arm of the firming wheel isconstructed from flat, plate material and thus presents a relativelynarrow profile which is easily received between the discs, an offsetjoggle in the arm is necessary in order to maintain the wheel on thecenterline of the discs, and such offset portion is positioned to therear of the discs so as to avoid interference problems. That section ofthe arm which is disposed to the rear of the discs is curved downwardlyin a manner to follow the contour of the discs as closely as possible soas to avoid the entrapment of trash and mud. A return spring on themounting arm of the wheel yieldably biases the wheel toward a lowerlimit position slightly below the discs so that during actual use thefirming wheel runs at or slightly above the bottom edge of the discsunder down pressure from the spring. In its preferred form, the wheel isa substantially smooth circular member constructed ofultra-high-molecular-weight polyethylene material, although analternative embodiment provides the wheel with an open spokeconstruction which allows the passage of soil through the space betweenits spokes.

An alternative seed firming wheel assembly is also included whichprovides wheel coupling structure associated with and extendingoutwardly from only one wheel surface, leaving the opposite wheelsurface, in the preferred embodiment, smooth from wheel center to rim.The coupling structure is adapted to rotatably couple the wheel to asupport member depending from an opener frame associated with the graindrill frame.

Various other objects and advantages, and features of novelty whichcharacterize the invention are pointed out with particularity in theclaims, annexed hereto and forming a part hereof. However, for a betterunderstanding of the invention and its advantages obtained by its use,reference should be had to the Drawings which form a further part hereofand to the accompanying descriptive matter in which there areillustrated and described several embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a grain drill employing a doubledisc opener having a seed firming wheel assembly associated therewith inaccordance with the principles of the present invention;

FIG. 2 is an enlarged, fragmentary elevational view thereof with thenear disc removed to reveal internal details of construction, certainparts being shown in cross-section for clarity;

FIG. 3 is a side elevational view of one embodiment of a seed firmingwheel in accordance with the principles of the present invention;

FIG. 4 is a vertical cross-sectional view through the firming wheelembodiment of FIG. 3;

FIG. 5 is a side elevational view of the double disc opener in use withthe near disc partially broken away to reveal the firming seed wheelassembly between the discs;

FIG. 6 is a fragmentary side elevational view similar to FIG. 5, butillustrating the firming wheel swung upwardly against the action of itsbiasing means to the limit of its upswinging travel;

FIG. 7 is a perspective view of a mounting bracket of the firming wheelassembly;

FIG. 8 is a slightly enlarged, transverse cross-sectional view of thefirming wheel of FIG. 5 taken substantially along line 8--8 of thatfigure;

FIG. 9 is a side elevational view of a second embodiment of the firmingwheel comprising a smooth, non-spoked wheel constructed ofultra-high-molecular-weight polyethylene;

FIG. 10 is a vertical cross-sectional view of the smooth wheel takensubstantially along line 10--10 of FIG. 9;

FIG. 11 is a side elevational view of the swingable mounting arm for thefirming wheel;

FIG. 12 is an end elevational view of the swing arm of FIG. 11 takensubstantially along sight line 12--12 thereof;

FIG. 13 is an enlarged, vertical cross-section view of the alternativefirming wheel embodiment;

FIG. 14 is a reduced vertical cross-sectional view through thealternative firming wheel embodiment as coupled to the downturnedlength, shown fragmented, of the S-shaped mounting arm;

FIG. 15 is a side elevational view of the sealing shield used with thealternative wheel assembly shown in FIG. 13;

FIG. 16 is a vertical cross-sectional view through the sealing shieldshown in FIG. 15 taken along the line 16--16;

FIG. 17 is an enlarged fragmentary, cross-sectional view of the bearingassembly seal as it appears before it is crimped into the bearing of thealternative wheel assembly shown in FIG. 13;

FIG. 18 is a side elevational view of the firming wheel shown in FIG.13, illustrating the bore and counter-bore relationship;

FIG. 19 is a vertical cross-sectional view of the firming wheel shown inFIG. 18 taken along the line 19--19 thereof;

FIG. 20 is a vertical cross-sectional view through the inner race of thealternative wheel assembly shown in FIG. 13;

FIG. 21 is a side elevational view of the nylon ball retainer showingthe spherical ball pockets;

FIG. 22 is an enlarged, vertical cross-sectional view of the bearingassembly associated with the alternative wheel assembly shown in FIG. 13showing the bearing seal in relationship to the rolling elements;

FIG. 23 is an enlarged, cross-sectional fragmented view of the annularopening and bonded downwardly pending flexible lip seal associated withthe sealing shield; and

FIG. 24 is a vertical cross-sectional view through the nylon ballretainer ring of the alternative wheel assembly shown in FIG. 13 takenalong the line 24--24 of FIG. 21.

DETAILED DESCRIPTION

The grain drill 10 illustrated in FIG. 1 may take a variety of differentforms within the scope of the present invention. For the sake ofillustration, the drill 10 comprises a "Solid Stand 3-point Drill"commercialized by the assignee of the present invention and disclosed insomewhat more detail as part of a folding drill in U.S. Pat. No.4,664,202. The '202 patent is hereby incorporated by reference into thepresent application as may be necessary for a full and completeunderstanding of the present invention.

The drill 10 includes a main transverse frame 12 which is partiallysupported by ground wheels 14 (only one being shown) located in front ofthe frame 12 and height-controlled by a vertically swingable mountingarm 16 and an extendible and retractable link 18. The arm 16 isswingably connected to the front of the frame 12 while the link 18extends between the front end of the arm 16 and the frame 12. A pair oflower 3-point mounting brackets 20 spaced along the front of the frame12 (only one of such brackets 20 being illustrated) and a third, upperbracket 22 located centrally between the two lower brackets 20 comprise3-point mounting structure for attaching the drill 10 to either the3-point hitch of a towing tractor or of a suitable pull-type frame. Aseed box 24 carried by the frame 12 delivers a steady supply of seedstoward the ground through a metering cup 26 and a flexible hose 28leading from the metering cup 26.

The drill 10 also includes a plurality of opener units 30 (only onebeing shown) secured to the frame 12 at spaced locations across thewidth of the machine according to the desired row spacing. Each of theopeners 30 includes a generally fore-and-aft extending sub-frame 32swingably mounted at its front end to the frame 12 via a transversepivot 34. Near the fore-and-aft midpoint of each sub-frame 32, thesub-frame is provided with a pair of side-by-side, downwardly andforwardly converging opener discs 36 and 38 that penetrate the soil to acertain depth as the drill is advanced and thus form a generallyV-shaped trench or seed groove in the soil. A slightly forwardlyinclined mounting bar 40 (FIGS. 2, 5, and 6) projects down fromsub-frame 32 on the fore-and-aft centerline of the opener unit andsupports the discs 36,38 for rotation about slightly downwardly andforwardly projecting axes of rotation. The bar 40 has a pair of nuts 44welded to opposite sides thereof at slightly downwardly and forwardlyinclined angles for receiving respective mounting bolts 45 of the discs36,38, each of the latter having its own bearing assembly journaled onthe corresponding bolt 45.

As illustrated in FIG. 2, a seed drop tube 48 is carried by eachsub-frame 32 and depends therefrom into the space between the forwardlyconverging discs 36,38 slightly ahead of the pivot shafts 44,46,although the lowermost discharge end 48a of the tube 48 is disposedbelow the pivot shafts 44,46 and substantially in fore-and-aft alignmenttherewith such that seeds gravitating from the drop tube 48 fall intothe trench immediately after its preparation by the converging discs36,38.

As shown in FIGS. 1 and 5, the depth of penetration of the discs 36,38is controlled and regulated by one or more press wheels 50 adjustablysecured to the rear end of the sub-frame 32. As well understood by thoseskilled in the art, the press wheel 50, which may be of a variety ofconfigurations, is mounted on a generally fore-and-aft extending leverarm 52 pivotally coupled at its front end with the sub-frame 32 via atransverse pivot 54. The lever arm 52 is held in a selected verticalposition about the pivot 54 by control mechanism 56 which operablyinterconnects the sub-frame 32 and the lever arm 52. A hand knob 58 ofthe control mechanism 56 allows the operator to adjust the position atwhich the lever arm 52 and the press wheel 50 are held relative to thediscs 36,38. Down pressure for the discs 36,38 is provided by one ormore compression springs 60 coiled about an upright guide rod 62 andtrapped between the sub-frame 32 and a shoulder 64 fixed to the rear ofthe frame 12 behind the seed box 24.

In accordance with the present invention, the opener 30 is provided witha seed firming wheel assembly broadly denoted by the numeral 66 andsituated generally between the press wheel 50 and the rear of the discs36,38. As illustrated in FIG. 2, the sub-frame 32 has a rigid, generallyupright strap 68 fixed thereto and depending therefrom which serves as aconvenient mounting means for the assembly 66. The strap 68 also servesas a convenient means for supporting a blade-type scraper 70 between theupper rear portions of the discs 36,38 for scraping away mud and othermaterials that might tend to accumulate between the discs in that area.

The strap 68 is slightly angled forwardly and carries along its frontside a complementally angled mounting bracket 72 of the wheel assembly66. The bracket 72 is shown in an isolated condition in FIG. 7, andreference may be made to that figure if need be for a full understandingof the nature and configuration of the bracket 72.

It will be noted that the bracket 72 includes an upper, relatively shortleg 74 having a threaded mounting hole 76 (FIG. 7) that receives athreaded fastener 78 which secures the leg 74 to the adjacent portion ofthe strap 68. Likewise, a lower, longer leg 80 of the bracket 72 has atransverse threaded hole 82 which receives a second threaded fastener 84passing through both the strap 68 and the scraper 70. The lowermost endof the leg 80 has an upwardly extending trash clearance notch 86, aswell as a pair of generally kidney-shaped mounting ears 88 that arerigidly fixed to the front face of the leg 80 on opposite sides of theclearance notch 86 and which project downwardly beyond the lowermostextremity of the leg 80. A rigid tab 90 projects forwardly from theupper leg 74 to serve as an attaching point for a tension spring 92which yieldably biases the wheel assembly 66 toward a lowered positionin a manner yet to be described.

The firming wheel assembly 66 also includes a generally S-shapedmounting arm 94 which is pivotally mounted intermediate its ends betweenthe two kidney-shaped ears 88 by a transverse pivot 96. As illustratedin FIGS. 11 and 12, the mounting arm 94 is formed from an initially flatpiece of plate material so as to present a relatively thin profile,except in those areas in which the arm 94 is joggled outwardly asdescribed hereinafter. A transverse hole 98 for the pivot 96 effectivelydivides the arm 94 into a front section generally denoted by the numeral100 and a rear section likewise generally denoted by the numeral 102.The front section 100 is upturned and is provided with a small hole 104adjacent its upper end which receives the lower end of the coil spring92 such that the spring 92 yieldably biases the arm 94 in a clockwisedirection viewing FIGS. 2, 5, 6, and 11. Along its inboard margin, thefront section 100 has a stop edge 106 which is disposed to abut theproximal front face of the bracket 72 when the mounting arm 94 is in theposition of FIGS. 2 and 5 whereby to limit the clockwise rotation of thearm 94. A somewhat similar although inclined stop edge 108 on theoutboard margin of the front section 100 of arm 94 is disposed to abutthe proximal disc mounting bar 40 when the arm 94 is rotated to theposition illustrated in FIG. 6. Thus, it will be seen that the arm 94 isadapted to rotate through an arc of approximately 30°, limited at itsopposite extremes by the bracket 72 and the disc mounting bar 40.

The rear section 102 of the mounting arm 94 has an upswept length 110immediately behind the pivot 96 and hole 98 followed by a downturnedlength 112 which is joggled out in a lateral direction relative to theplane of the upswept length 110 and the front section 100. Asillustrated in FIG. 2, the upswept length 110 is just long enough toreach the rear periphery of the discs 36,38, at which point thedownturned length 112 begins and extends immediately to the rear of therear periphery of the discs 36,38. It will be seen that when the arm 94is in the lower position of FIGS. 1, 2, and 5, the forward edge of thedownturned length 112 generally conforms to and is in close proximitywith the rear arcuate periphery of the discs 36,38 so as to limit theopportunity for trash materials to become trapped between the rear ofthe discs 36,38 and the downturned length 112 of the arm 94.

As illustrated in particular in FIG. 12, the joggled out downturnedlength 112 includes an initial outturned segment 112a, an intermediateparallel segment 112b which is parallel to the upswept length 110 andthe front section 100, an inturned, return segment 112c approximatelyhalf the length of the outturned segment 112a, and a final tip portion112d which lies in a plane parallel to the upswept length 110 and theintermediate segment 112b. The tip portion 112d is provided with anopening 114 which serves to mount a transverse stub axle shaft 116associated with a firming wheel 118 of the assembly 66.

It will be understood that the wheel 118 is ideally disposed on animaginary, fore-and-aft centerline passing between the discs 36,38 suchthat the wheel 118 rides within the trench formed by the discs 36,38during use. Such strategic positioning of the wheel 118 is achieved byvirtue of the joggled nature of the downturned length 112 of the rearsection 110 of mounting arm 94. It will also be noted from FIGS. 1 and 2in particular that the joggled downturned length 112 is positioned tothe rear of the periphery of the discs 36,38 so as not to interfere withthe free rotation of the two discs 36,38 themselves, notwithstanding theadditional width inherent in the otherwise flat mounting arm 94 affordedby the joggled portion. It will also be noted that because of theintimate relationship between the downturned length 112 of the arm 94and the rear periphery of the discs 36,38, the wheel 118 isclose-coupled with the discs 36,38 and in fact has its forward halfprojecting into the space between the two discs.

It is to be noted that the parts of the firming wheel assembly 66 are soconfigured and arranged that when the stop edge 106 of arm 94 is againstthe bracket 72 as in FIGS. 1, 2, and 5, the wheel 118 projects a shortdistance down below the lowermost extremity of the discs 36,38. However,the coil spring 92 is so designed as to permit the wheel 118 to readilyswing up out of its lowermost position in the event obstacles such asclods, stones, or trash materials are encountered. In fact, the springforce of spring 92 is selected so that, in use, the firming wheel 118 isincapable of bearing the weight of the opener 30 and serving as thedepth gauging means in lieu of the press wheel 50. In one exemplaryembodiment, a spring having a spring rate of 27.5 lbs. per inch with 8.8active coils and a maximum extended length of 43/8 inches has been foundto be effective. The initial tension of such spring is approximately 7.1lbs.

As shown best in FIGS. 8 and 12, the downturned length 112 of the arm 94is twisted slightly out of a truly vertical plane on the order ofapproximately 5°, (except for the tip 112d) so that its leading edge 120is spaced slightly farther away from the proximal surface of the wheel118 than the trailing edge 122. Thus, in effect, the downturned length112 in portions 112a, 112b, and 112c thereof diverges outwardly awayfrom the proximal surface of the wheel 118 in a forward direction withrespect to the normal path of travel of the firming wheel assembly 66,such diverging relationship helping to release mud and trash materialsthat might otherwise become trapped between the downturned length 112and the wheel 118.

The wheel 118 illustrated in FIGS. 1-8 represents one embodiment of awheel usable in accordance with the present invention. Such wheel 118 ispreferably molded from a synthetic resinous material such as Xenoy-6370which is available from General Electric Company. A central, circularhub 124 of the wheel 118 has a concentric bore 126 therethrough which isdefined by a molded-in bearing 128 journaled on the pivot 116 at thelower end of the arm 24. An outer rim 130 of the wheel 118 is joinedwith the hub 124 by three radially extending, circumferentially spacedapart spokes 132 disposed at 120° intervals about the periphery of theinner hub 124.

In some conditions, the open spaces 134 between the spokes 132 may tendto trap stalks and other materials during field use of the equipment,although the spaces 134 also permit the pass-through of soil and clods.Thus, a preferred form of the firming wheel, if accumulation of foreignmaterial between the spokes 132 is a concern, is illustrated in FIGS. 9and 10 and is denoted broadly by the numeral 218. It will be seen thatthe wheel 218 is constructed from a smooth circular block of syntheticresinous material and has no spokes or spaces between such spokes aspart of its configuration. Instead, the opposite sides of the smoothwheel 218 simply comprise flat faces 218a and 218b which extend from theoutermost periphery 218c to an inner circular periphery 218d, at whichlocation a bearing assembly 220 is located. The bearing assembly has acentrally defined bore 222 therethrough which receives the pivot pin 116of the wheel assembly 66. An annular retaining flange 224 is secured tothe face 218a of the wheel 218 by a plurality of screws 226 to assurethat the bearing assembly 220 remains seated against an internalshoulder 228 within the wheel 218. In its preferred form, the smoothwheel 218 is formed from an ultra-high-molecular-weight polymer (UHMW)which is selected because of its extremely high abrasion resistance, itsexceptional impact resistance and its non-stick surface characteristics.Thus, the wheel 218 is relatively long wearing, yet resists theadherence and accumulation of mud and other materials to its varioussurfaces. One source of the product is the Poly Hi Company of Ft. Wayne,Ind., as 5/8 inch thick black static-reduced TIVAR-100 having amolecular weight of 4.5-5.67 million.

Experience has shown that in operation, wheel bearing effectiveness canbe adversely affected by the unacceptably high level of dirt, residueand trash entry through bearing seals into the bearing internalstructure. Experience has also shown that high level of bearing sealdrag can be experienced with conventional wheel-bearing design when usedin wet soil conditions. Thus an alternative preferred form of thefirming wheel, is illustrated in FIGS. 13 through 22 and is broadlydenoted by the numeral 318. Wheel 318 is constructed from a smoothcircular block of synthetic resinous material, such as UHMW (aspreviously described), and has no spokes or spaces such as spokes aspart of its configuration. Instead, opposite sides of the smooth wheel318 simply comprise a first flat face 318a and a second flat wheelcoupling face 318b. Face 318a presents a smooth surface extending fromthe outermost periphery 318c to wheel center 318d. Wheel coupling face318b includes a concentric bore 319 located thereon and extendingpartially through wheel 318 as shown in FIG. 19. Bore 319 presents ablind face 319a therein and is adapted to receive an alternative bearingassembly 320. A concentric counter-bore 319b is positioned radiallyoutwardly from bore 319 on the second flat wheel coupling face 318b, asshown in FIGS. 18 and 19, and is shallower than concentric bore 319.

Alternative bearing assembly 320 includes an inner race 322 and an outerrace 324 with rolling elements 325 located therebetween to permitrelative movement between inner and outer races 322, 324. As shown inFIGS. 13, 20, 21 and 22, races 322 and 324 present interior and exteriorplanar faces 322a, 324a, 322b and 324b, respectively.

As shown in FIG. 20, inner race 322 includes first and second outerperipheral surfaces 322c and 322d effectively divided by inner racebearing surface 322e. As shown in FIGS. 13 and 22, outer race 324includes first and second outer race annular surfaces 324c, 324d,effectively divided by an outer race bearing surface 324e.

A nylon ball retainer ring 326 is provided to maintain the spacedrelationship between rolling elements 325, as shown in FIG. 21. Retainerring 326 includes a plurality of roller dividing elements 326a withrecessed roller pockets 326b located therebetween for receiving rollingelements 325.

As shown in FIG. 20, a shaft portion 328 is concentrically positioned oninner race exterior face 322b and extends outwardly therefrom. Thediameter of shaft portion 328 is less than the diameter of inner raceexterior face 322b. Shaft portion 328 includes a cylindrical outersurface 328a with opposite end 328b including a concentric threadedchamfer 328c and an off-center, roll-preventer pin bore 328d including apin 328e securely inserted therein and extending outwardly therefrom, asshown in FIGS. 13, 14 and 20. Shaft opposite end 328b is adapted tofixedly attached to alternative tip portion 312d by means of a bolt 328fsized to extend through opening 314 and threadably engage threadedchamfer 328c. Alternative tip portion 312d is also provided with a smallaperture 315, as shown in FIG. 14, to securely receive roll preventerpin 328e

Concentric bore 319 is adapted to tightly receive bearing assembly 320wherein inner race interior face 322a and outer race interior face 324aabut concentric bore blind face 319a.

As shown in FIGS. 13, 14, 17 and 22, a bearing seal is general referredto by the numeral 330 and includes an outer rim 332 fixedly attached toouter race first annular surface 324c. Bearing seal 330 further includestwo continuous radially inwardly extending flexible lips 334,336depending from rim 332 and adapted to be in wiping engagement with innerrace first outer peripheral surface 322c. In its preferred form,flexible lips 334, 336 are made of rubber-like material and obtainedfrom Delta Rubber Company of Danielson, Conn.

As shown in FIGS. 15 and 16, a sealing shield 340 is provided forrestricting the introduction of undesirable materials such as dirt,residue and trash into bearing assembly 320. Sealing shield 340, in thepreferred embodiment, is formed by stamping sheet metal and includes aring portion 342 and an annular region 344 extending therefrom. The ringportion 342 is provided with bolt holes 346, as shown in FIG. 15. Thering portion 342 is adapted to be piloted by and in registry with theconcentric counter-bore 319b; thus, providing a snug fit so that asmall, generally uniformly continuous clearance is provided betweenannular opening 350 and shaft cylindrical outer surface 328a.Counter-bore 319b further pilots ring portion 342 so that there is asubstantially continuous wiping engagement between flexible lip 354 andouter cylindrical surface 328a. Wheel 318 is provided with threaded boltholes 348 which correspond and are adapted to be in registry withsealing shield bolt holes 346. Ring portion 342 is adapted to bedisposed against outer race 324 when bolted in concentric counter-bore319b to secure bearing assembly 320 in concentric bore 319. Annularregion 344 has an opening 350 for receiving shaft 328 therethrough.Opening 350 is sized so that there is a small clearance provided betweenopening 350 and shaft cylindrical outer surface 328a, as shown in FIGS.13 and 22. A shield seal 352 is affixed to internal surface 344a andincludes a continuous radially inwardly extending flexible lip 354adapted to be in wiping engagement with said shaft outer cylindricalsurface 328a to form a seal therewith. In the preferred embodiment,shield seal 352 is a rubber-like material which can be bonded tometallic surfaces and is a black nitrile buna "N" rubber, 60-70durometer (hardness) shore "A".

As with wheel 118, alternative wheel embodiments 218 and 318 are, in thepreferred embodiment, disposed on an imaginary, fore-and-aft centerlinepassing between the discs 36, 38 such that the wheel, whether wheel 218or 318, rides within the trench formed by the discs 36, 38 during use.As before discussed, the strategic positioning of wheel 118,218, or 318along the vertical axes (shown in FIG. 14 for the embodimentincorporating wheel 318) is achieved by virtue of the joggled nature ofthe downturned length 112 near section 110 mounting arm 94.

Operation

As the drill 10 advances and the discs 36, 38 prepare a seed receivingtrench in the soil, the seeds are dropped into the trench through thedrop tube 48 and are immediately engaged by the firming wheel 118, 218,or 318 if the smooth wheel version is utilized. Regardless of which ofthe wheels 118, 218, or 318 is selected for use, the gentle, seedfirming action is the same in either case.

Using the wheel 118 for purposes of illustration, it will be appreciatedthat the wheel 118 does not bear the weight of the opener 30 or in anyway detract from the full functional effect of the gauging press wheel50. Instead, because of the light-duty nature of the spring 92, thewheel 118 rides only gently over the deposited seeds and gives them afinal firming touch that sets them down into the loose, moist soil atthe bottom of the trench. Thus, all of the seeds are more assured ofbeing set into the soil at precisely the same depth, which results inmore uniform germination and emergence. In the event some loose soil mayhave slipped into the trench slightly covering the seeds before thewheel 118 comes along, such soil will simply be firmly covered over theseeds such that the seeds are still gently tucked down into the seed bedat the proper depth.

As illustrated, for example, in FIG. 2, the firming wheel 118 isnormally set to project down slightly below the bottom extremity of theopener discs 36,38. However, under actual running conditions, the arm 94will be swung upwardly to a slight extent so that the firming wheel 118is no deeper than the discs 36,38 and the spring 92 provides anappropriate amount of down pressure to the wheel 118 as it rolls in thetrench. In the event a large obstacle is encountered by the wheel 18,the arm 94 can yield substantially upwardly as illustrated in FIG. 6until the stop edge 108 abuts the bar 40, limiting such movement. Asearlier described, the downward extent of movement of the firming wheel118 is determined by the stop edge 106 as it abuts against the mountingbracket 72.

The design of the firming wheel assembly 66 is such as to minimize thecollection and adherence of trash materials and mud. In this regard,having the wheel mounting portion of the arm 94 turned downwardly sothat it normally extends in a generally upright attitude as exemplifiedby the down swept length 112 helps shed materials that would otherwisetend to accumulate in that area. Moreover, having the downturned length112 positioned in close, intimate proximity to the rear edge of thediscs 36,38 minimizes the space available for materials to become wedgedbetween the trailing periphery of the discs 36,38 and the downturnedlength 112. As earlier mentioned, the slightly arcuate nature of thedownturned length 112 as it conforms generally to the rear peripheriesof the discs 36,38 also helps in this respect.

Also of significance is the fact that the downturned length 112 of thearm 94, with the exception of the lowermost tip portion 112d, is flaredoutwardly away from the proximal surface of the wheel 118. Thus, mud,soil particles, and trash residue that might tend to cling to theupwardly moving rear periphery of the wheel 118 and approach thedownturned portion 112 are immediately released after passing thedownturned portion 112, instead of being wedged into a more confinedenvironment. This helps keep the wheel 118 rolling so that it does notskid and gouge along the bottom of the seed trench. The plastic natureof the wheels 118 and 218 is also helpful in that non-stick surfaces arethus provided so that the wheels more readily shed soil particles thatwould otherwise tend to adhere to such surfaces.

The invention embodied in wheel 318 further reduces collection andadherence of trash materials and mud to firming wheel assembly 66because smooth, flat smooth face 318a allows trash materials and mud toflow by wheel 318 and not hang up on a fastener used to mount the wheelor to retain a bearing. In addition, seal drag is reduced becausebearing assembly 320 requires only one seal since the interior faces322a and 324a of inner and outer races 322,324 are protected by theblind face 319a of concentric bore 319. Seal drag is further reducedbecause the reduced diameter of the shaft portion 328 results in smallersealing engagement surface area.

Although preferred forms of the invention have been described above, itis to be recognized that such disclosure is by way of illustration only,and should not be utilized in a limiting sense in interpreting the scopeof the present invention. Obvious modifications to the exemplaryembodiments, as hereinabove set forth, could be readily made by thoseskilled in the art without departing from the spirit of the presentinvention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of theirinvention as pertains to any apparatus not materially departing from butoutside the literal scope of the invention as set out in the followingclaims.

We claim:
 1. In an opener having seed trench forming means and atrailing seed firming wheel assembly disposed to extend into the trench,the improvement comprising:a mounting member; a firming wheel, saidwheel including an outermost periphery, a central axis, an upright,fore-and-aft extending, outside surface smooth from the central axis tothe outermost periphery and facing away from said member, and anopposite, upright, fore-and-aft extending inside surface facing towardsaid member; and structure projecting outwardly from said inside surfacerotatably coupling said firming wheel to the member.
 2. In an opener asclaimed in claim 1,said structure including a spindle shaft fixed tosaid member and rotatably supporting the wheel for rotation about theaxis of the shaft.
 3. In an opener as claimed in claim 2,said spindleshaft having an outer end abutting said member and an internallythreaded hole coaxial with said axis of rotation and extending inwardlyfrom said end of the shaft, said member having a clearance openingaligned axially with said threaded hole of the shaft, said memberfurther having a threaded fastener passing through said clearanceopening in the member and into threaded engagement with said hole of theshaft for securely fixing the shaft to the member.
 4. In an openerhaving seed trench forming means and a trailing seed firming wheelassembly disposed to extend into the trench, the improvementcomprising:a mounting member; a firming wheel, said wheel including anoutermost periphery, a central axis, an upright, fore-and-aft extending,outside surface smooth from the central axis to the outermost peripheryand facing away from said member, and an opposite, upright, for-and-aftextending inside surface facing toward said member; and structureprojecting outwardly from said inside surface rotatably coupling saidfirming wheel to the member, said structure including a spindle shaftfixed to said member and rotatably supporting the wheel for rotationabout the axis of the shaft, said spindle shaft comprising part of abearing assembly permitting rotation of the wheel relative to themember, said inside surface having a recess configured to receive saidbearing assembly, said recess having a floor spaced inwardly from saidoutside surface of the wheel to render said outside surface smooth. 5.In an opener as claimed in claim 4,said spindle shaft having a radiallyoutwardly facing surface disposed within said recess that forms an innerrace of the bearing assembly, said bearing assembly further including anannular outer race circumscribing said inner race in radially outwardlyspaced relation therewith, and a ring of anti-friction roller elementsconfined between the inner and outer races.
 6. In an opener as claimedin claim 5,said bearing assembly further including an annular moistureseal around the inner race outwardly adjacent the ring of rollerelements and spanning the distance between the inner race and the outerrace.
 7. In an opener as claimed in claim 6,said wheel having an annularshield on said inside surface thereof disposed in concentricrelationship with said axis of rotation, said shield having a centralclearance opening through which said shaft extends, said shield furtherhaving a marginal portion disposed radially outwardly from said centralopening and secured to the wheel, said shield overlapping said outerrace of the bearing assembly to retain the bearing assembly in saidrecess of the wheel.
 8. In an opener as claimed in claim 7,said shieldhaving a second annular moisture seal circumscribing said spindle shaftin axially spaced relation with the first-mentioned seal and in wipingengagement with the spindle shaft.
 9. In an opener as claimed in claim8,said shield having a central boss portion in a different plane thansaid marginal portion, said second seal being located at said bossportion of the shield.
 10. In an opener as claimed in claim 9,saidspindle shaft being stepped to present a reduced diameter portion at thepoint of passage through said central opening of the shield and anenlarged diameter portion at said inner race, said first seal bearingagainst said enlarged diameter portion and said second seal bearingagainst said reduced diameter portion.
 11. In an opener as claimed inclaim 5,said wheel having an annular shield on said inside surfacethereof disposed in concentric relationship with said axis of rotation,said shield having a central clearance opening through which saidspindle shaft extends, said shield further having a marginal portiondisposed radially outwardly from said central opening and secured to thewheel, said shield overlapping said outer race of the bearing assemblyto retain the bearing assembly in said recess of the wheel.
 12. In anopener as claimed in claim 11,said spindle shaft being stepped topresent a reduced diameter portion at the point of passage through saidcentral opening of the shield and an enlarged diameter portion at saidinner race, said shield having an anti-moisture seal thereoncircumscribing said reduced diameter portion of the spindle shaft inwiping engagement therewith.
 13. In an opener as claimed in claim12,said bearing assembly including an additional anti-moisture sealoutwardly adjacent said ring of roller elements in wiping engagementwith the enlarged diameter portion of the spindle shaft.
 14. In anopener as claimed in claim 13,said shield having a central boss portionin a different plane than said marginal portion, said central openingand said anti-moisture seal for the reduced diameter portion of theshaft being located at said boss portion of the shield.
 15. In an openerhaving seed trench forming means and a trailing seed firming wheelassembly disposed to extend into the trench, the improvementcomprising:a mounting member; a firming wheel, said wheel including anoutermost periphery, a central axis, an upright, fore-and-aft extending,outside surface smooth from the central axis to the outermost peripheryand facing away from said member, and an opposite, upright, fore-and-aftextending inside surface facing toward said member; and structureprojecting outwardly from said inside surface rotatably coupling saidfirming wheel to the member, said structure including a spindle shaftfixed to said member and rotatably supporting the wheel for rotatingabout the axis of the shaft, said spindle shaft having an anti-rotationpin projecting therefrom into retaining engagement with said member toprevent rotation of the shaft with the wheel.